1. Field of the Invention
The present invention relates to a brine for use in preserving various foods and biological samples without causing contamination thereto. The present invention also pertains to a method for preserving various foods and biological samples with a brine, such as by freezing, so as not to cause contamination to the preserved items by the brine.
2. Description of the Related Art
Methods of freezing food products for long time preservation or biological samples for cytological or histological examination are known and available. For example, liquid nitrogen is a conventional method for freezing food or biological samples. Nevertheless, this method is costly since the liquid nitrogen is expensive. Moreover, there may be damage to the cellular structure of the foods or biological samples, which in turn results in deterioration in the quality of the foods, or interferes with a rapid and accurate examination of cryogenically frozen tissue.
Using a cooled brine (antifreeze solution) is another conventional freezing method. Brine includes inorganic substances such as calcium chloride, and organic substances such as ethylene glycol, and propylene glycol. Furthermore, the solution prepared by mixing the above ingredients is advantageous in that greater cooling is achieved at a comparatively lower price.
For example, “A Method of Freezing Fishery Products” is known from U.S. Pat. No. 4,601,909 issued to Nagoshi on Jul. 22, 1986. This method includes the steps of preparing a brine containing rapeseed oil, propylene glycol, calcium chloride and water, cooling the brine and immersing the seafood in the cooled brine until it is frozen. This method reduces or eliminates breakdown of muscle tissue in the seafood. Hence, deterioration in quality of the frozen product is prevented or reduced.
A similar process for “Quick Freezing of Meat” is disclosed and claimed in U.S. Pat. No. 4,654,217 issued to Nagoshi on Mar. 31, 1987. The process disclosed in this later patent is similar to that disclosed in the earlier patent except that it is applicable to beef, poultry, pork and the like.
U.S. Pat. No. 4,657,768 issued to Nagoshi on Apr. 14, 1987, discloses a “Freezing Method for Perishable Foods” which includes placing a perishable food in a heat conducting container and causing the other surface of the heat conducting container to contact cooled brine or a liquefied gas. Accordingly, the perishable food is frozen quickly without immersion.
U.S. Pat. No. 4,689,963 issued to Sakai on Sep. 1, 1987, relates to a method of freezing foods. The method of Sakai is similar to the methods of Nagoshi except that a layer of brine is placed in the heat conducting container along with the perishable food. Freezing proceeds only from the portion which is in contact with the brine and the potential for the food to stick to the container is reduced.
U.S. Pat. No. 4,840,035 provides a method of freezing a tissue specimen by using a brine comprising a cruciferous oil.
None of the aforementioned patents addresses the potential problem that the chemical ingredients of the brine may enter into the package of the foods or biological samples during the freezing process, when the package develops a puncture or tear and is compromised. Thus, the brine may contaminate the frozen foods or biological samples, and causes problems such as deteriorating the quality of the foods; causing an unpleasant or undesired taste of the foods; and interfering with rapid and accurate examination of the frozen biological samples.
Accordingly, it is desirable to find a simple, convenient, and effective freezing method, which can facilitate the identification and separation of the contaminated frozen products. In addition, there is also a need to further improve the efficiency of the freezing or the freezing capacity per unit volume of brine.